1. Field of the Disclosure
The present disclosure relates to a self-pinned-type magnetic detecting element.
2. Description of the Related Art
Usually, a magnetic sensor including a magnetic detecting element has been paired with a permanent magnet, and, for example, in an automotive sensor, environment resistance in a magnetizing field of several tens or more of mT has been important under a high-temperature environment of 100° C. or more.
On the other hand, in the case of a geomagnetism sensor used for a mobile phone or the like, a capability for detecting geomagnetism with a high sensitivity is desirable without using a permanent magnet. In the case of the geomagnetism sensor, while higher heat resistance than an automotive sensor or the like has not been desired, good disturbance noise tolerance has been desired so as to maintain a stable high sensitivity characteristic.
U.S. Pat. No. 6,972,934 discloses a magnetic detecting element utilizing an antiferromagnetic layer is disclosed. However, in the magnetic detecting element utilizing an antiferromagnetic layer, magnetic field heat treatment is desired that is used for assigning unidirectional anisotropy of a fixed magnetic layer without dispersion. Therefore, owing to the magnetic field heat treatment, a free magnetic layer is also assigned with an easy axis in the fixed magnetization direction of the fixed magnetic layer. Accordingly, the coercive force Hc of the free magnetic layer becomes large, and hence, it has been difficult to obtain a small coercive force Hc suitable for the geomagnetism sensor. As a result, there has occurred a problem that, owing to a ΔMR characteristic (ΔMR-H curved line; the ΔMR indicates a resistance change rate (ΔR/R), and the H indicates an external magnetic field), a hysteresis becomes large, linearity is poor, and detection accuracy is reduced.
On the other hand, as illustrated in U.S. Pat. No. 5,583,725, in the case of a self-pinned-type magnetic detecting element, since the self-pinned-type magnetic detecting element has a structure not including an antiferromagnetic layer, the magnetic field heat treatment may be unnecessary.
In a self-pinned type, there has occurred a problem that when a strong external magnetic field (disturbance magnetic field) is applied, a fixed magnetic layer including an artificial-antiferromagnetic (AAF) structure is subjected to magnetization dispersion, the deterioration rate of a ΔMR (resistance change rate) becomes large, and furthermore, the output fluctuation of a geomagnetism sensor becomes large. In other words, in a self-pinned-type magnetic detecting element of the related art, it has been difficult to obtain good disturbance noise tolerance. While a geomagnetism sensor detects weak geomagnetism (a magnetic field to be detected), since a strong external magnetic field (disturbance magnetic field) from a speaker or the like easily affects the geomagnetism sensor under a circumstance that the geomagnetism sensor is embedded in a mobile phone or the like, in particular it may be important to improve the disturbance noise tolerance, compared with heat resistance or the like.
While U.S. Pat. No. 5,583,725 discloses a self-pinned-type magnetic detecting element, in U.S. Pat. No. 5,583,725, the structure of a magnetic detecting element is not disclosed that is suitable for improving the disturbance noise tolerance with respect to a case where the self-pinned-type magnetic detecting element is applied to a magnetic sensor such as a mobile phone, which does not embed therein a permanent magnet.
These and other drawbacks exist.